Imagine a perfect steak - a hunk of wagyu evenly cooked to a sublime medium rare, sizzlingly sealed with its juices threatening to overflow. This perfect steak can now be a reality any time by putting the meat in a plastic bag, vacuum sealing it, and cooking it to an exact 62.5 degrees Celsius, followed by a quick flash on the grill. Welcome to the meticulous world of sous vide.

Sous vide - 'under vacuum' in French - involves vacuum-sealing ingredients in a bag and cooking them in a water bath set to a designated temperature. Food shrinkage and liquid loss happen when the cooking temperature exceeds the optimal level suitable for the food. When that happens to proteins, the muscle fibres stretch longitudinally, squeezing liquid out. The resulting loss in flavour and moisture is why many chefs turn to sous vide for a more controlled cooking process.

Sous vide takes longer than traditional methods - an 8 ounce steak takes 22 minutes in the water bath, a lifetime for the hungry diner. However, the beauty of this process is that each ingredient is uniformly cooked throughout and is never heated above its optimal temperature - meaning it cannot burn and a few extra minutes in the bath will not affect the quality of the food. The optimal temperature varies according to the ingredients. For a wagyu steak it is 55 degrees Celsius for rare and 62.5 degrees for medium rare, while salmon can be cooked to tender perfection at 42 degrees.

These temperatures were determined by Jason Black, general manager of Frog Face Fish and Zest, two restaurants on Wyndham Street. The chefs at the two venues 'love the machines', Mr Black says, adding that chef Zero Yu, the new head chef at Frog Face Fish, previously worked at a restaurant in Australia renowned for using sous vide. With the water bath slowly cooking the food, the chefs have more time to concentrate on fine-tuning the sauce or other components of the dish.

This reliance on the water bath, decades ago, prompted a controversy about whether those in the industry who cook using the sous vide technique can really call themselves chefs. Given that science determines the optimal temperatures for cooking each ingredient, some have called into question the skills of a chef who cooks by numbers rather than the old-fashioned way - poking and prodding over a sizzling grill.

Joel Robuchon, a renowned French chef who operates several restaurants worldwide, including Hong Kong's L'Atelier de Joel Robuchon, has been using the technique for more than 20 years and he disagrees that it is not real cooking.

'The people who say that [sous vide is cheating] do not understand this technique,' he says.

Contrary to the idea that the bath 'baby-sits' the food in lieu of the chef's careful attention, Robuchon says that the technique 'requires a high level of skill, expertise, knowledge and time'. Some of the finer points of the technique include de-airing, texture modification and becoming familiar with health and safety regulations. Chefs in Hong Kong who use the technique also speak in defence of using technological innovations in the kitchen.

Chef Mauro Uliassi of Italian restaurant Domani describes the increasing use of science in the kitchen not as a mere fad but 'an evolution of the kitchen'. He says that scientific techniques in no way preclude traditional cooking methods, that proteins cooked in a water bath can always be pan-fried quickly afterwards for a traditional crust or crispy skin in addition to the benefits of sous vide.

For those looking to experiment, sous vide opens the door to a new world of flavours and textures. Chefs have used the vacuum to compress fruit, such as watermelon and pineapple, for a different texture and a more concentrated taste. Others, including Oyvind Naesheim, executive chef of Nobu at the InterContinental Hong Kong, have taken it a step further by vacuum sealing ingredients with sauces for an unexpected twist.

'We can infuse a flavour into beef before roasting it, creating a 'melt in your mouth' experience,' Naesheim says. 'We do this with a variety of sauces for wagyu beef, in addition to salmon with jalapeno dressing, pork loin with wasabi salsa and lamb rack with anticucho sauce.'

The science even makes the impossible possible when slow-cooking proteins such as hare or rabbit. Chef Frederic Chabbert from French restaurant Petrus, who cooks Beauce hare sous vide, says wild rabbit requires 36 consecutive hours of cooking at 62 degrees to break down the muscle and tissue and concentrate the flavour. 'It's not feasible to have a chef stand over the rabbit for that length of time to constantly moisten the meat,' he says.

Ultimately, 'no technology is a cheat', says Mr Black, comparing the use of sous vide to the use of a mixer in making mayonnaise - something that modern chefs now take for granted without so much as a glance back to the old mortar and pestle days.

However, he acknowledges that some things, such as pastry, simply have to be done by hand to produce the high quality of texture and taste that diners expect. A chef's work in the kitchen has always been devoted to delivering quality food to a satisfied client, he says, 'and this will never change, despite the onward march of technology'.